The invention relates to monitoring arrangements for sowing machines, particularly for row drills having a large number of rows or coulters.
It is well known that in agriculture one of the determinants of the yield is the quality of the sowing. In large-scale agricultural operations seeding machines or row drills are now being widely used that have a large number of rows or positions so as to increase productivity. For grain sowing machines, the number of coulters sometimes exceeds 140. If therefore serious production losses are to be avoided one has to become promptly aware of any blocking of the coulters, including the circumstance that the seed should run out from the seed box.
Various devices became known for monitoring the operation of sowing machines, mainly for machines having a small number of rows or positions (max. 16 coulters), aiming at automatically indicating to the tractor driver if there is a sowing irregularity. The driver eliminates the disturbance and then proceeds with the sowing. It is a common characteristic of these devices that the coulters are provided with a photocell-operated unit that senses the interruption in sowing. The seed leaves the coulters upon having interrupted the light beam of the photocell. In the sensing units, pulse sequences are produced that have a frequency corresponding to the seed flow. When the flow is interrupted, that is in the event of a sowing disturbance, the pulse sequence is interrupted. Separate lines or conductors are provided to link the individual sensing units of the coulters to an electronic fault-location indicating unit that is disposed within the field of vision of the tractor driver. In such arrangements the electronic unit gives an indication of the location and possibly the number of the disturbed coulters by the intermediary of illuminated signal lamps when the pulse sequence of the sensing unit(s) is interrupted. Such a solution is known for example from the U.S. Pat. No. 3,723,989, and the commercially known VEK-6 and -8 sowing monitoring arrangements are basically of the same principle.
The indication of the faulty location is consequently provided with these solutions in a central unit, by the intermediary of the positional numbers of the coulters that are involved. These devices being almost exclusively adapted to seeding machines that have a relatively low number of rows or coulters (6, 8 or 12) it is usually not difficult for the driver to memorize the number of the faulty coulter.
As mentioned above, there are as many lines or conductors for carrying information from the sensing units of the coulters as there are coulters, providing individual information at the central unit. Such wires or lines can be bundled into a multi-line cable or into a composite conductor. With a small number of coulters there are no particular difficulties in leading the lines from the seeding machine to the driver's seat, and the performance of the arrangement is not essentially influenced.
If however the known solutions are to be used for seeding machines having a high number of rows (such as 48), we are facing serious difficulties. One of them is that the tractor driver has to memorize one or more position numbers for the faulty coulters so that difficulties may be encountered in selecting the non-operating coulter, which may require re-checking, and may become rather time consuming. A further disadvantage resides in that a substantial amount of cable becomes necessary which, besides the initial expenditures, seriously impairs the operational reliability of the operating machine unit. This is further compounded by the fact that the arrangement becomes rather expensive on account of the use of opto-electronic sensing units and the substantial number of indicating lights, furthermore involving substantial electric energy consumption. On account of the enumerated deficiencies and difficulties the sowing monitoring of multi-row machines has not been solved so far.